Magnetically driven fluid pump manufacturers supply outer drive magnet assemblies that are mounted or attached to the output shaft of an electric motor. The outer drive magnet assembly is typically disposed on the motor output shaft and held in place using a shaft key and a set screw. The outer drive magnet assembly rotates with the motor output shaft. The outer drive magnet assembly of several manufacturers are one-piece assemblies. Manufacturers of such devices include Ansimag Inc. of Elk Grove, Ill.
Outer drive magnet assembly characteristics vary in accordance with required magnet strength, horsepower (hp) requirements of the pump, RPM (revolutions per minute) of the motor and the bore and keyway dimensions of the motor output shaft. The same outer drive magnet assembly can be used with several horsepower and RPM ranges. For example, the same magnet assembly can be used for 1 hp through 5 hp pumps operating at 3500 RPM. A different magnet assembly may be used for 7.5 hp through 15 hp at 3500 RPM. The internal bore and keyway dimensions of the shaft to which the magnet assembly is attached are the only differences in the outer drive magnet mechanisms for several horsepower and RPM ranges. Manufacturers currently address this difference by fabricating completely different outer drive magnet assemblies for each different motor shaft diameter. The outer drive magnet mechanism is quite costly relative to the total cost of the pump. The added cost is passed on to distributors and end users of the outer drive magnet mechanism. The outer drive magnet mechanism is costly to manufacture, expensive to maintain as an inventory item (for manufacturers, distributors and end users) and occupies valuable inventory shelf space.
There is a need for an adapter mechanism to make the outer drive magnet assemblies more versatile in their application. Creating added versatility in the application of outer drive magnet assemblies can reduce manufacturing overhead costs and thus reduce purchasing and inventory costs to manufacturers, distributors and end users. End users would benefit in that they would only be required to stock the largest bore diameter outer drive magnet assembly for each pump/horsepower/RPM range, along with the appropriate adapter, thereby reducing inventory costs and adding flexibility and convenience in replacing outer drive magnet assemblies.